Process for the manufacture of camphor from borneol or isoborneol.



UNITED sirn'rns PATENT oFFion GARL R IIDER, OE WANDSBEK, NEAIR HAMBURG, GERMANY.

ROCESS FORLTHE MANUFACTURE OF CAM'PHOR FROM BORNEOL OR ISOBORNEGJ;

No Drawing.

To alll wlro m-itmay concern it known that I, Cairn RUDER, doctor of. philosophy, analytical chemist, a subject ofi the Kin'gofi Bavaria,"residing at \Vandsbek, near Hamburg, in the State of Prussia, German Empire, hiwe invented certain new and' useful. Improvements in Processes for the Miini faoture of Camphor from Borneol or Isoborneol, of which'the following is a specification. I

It has already been' proposed to convert borneol' or'its equivalent isoborneolinto carnphor by oxidation with chromic acid. It has however been a diflicultmatter to carry out that recess in such a manner as to produce a use I i! oomphor in large quantity free from borneol.

When it is attempted to oxidize borneol directly, that is without the addition of a solvent, the reaction is extremely slow and is never: complete If solutions of borneol or isoborneol are employed in any non-oxidizahjle solvent the action of chromic acid, even withj-the use of very dilute solutions of chromic acid, is so violent that the oxida" tion progresses to such an extent as to diminish the yield veryconsiderably. It has been attempted to prevent these byreactions and the formation of condensation prdglucts by adding sulfa-nilic acid or similar compounds to the chromic acid mixture. This method 'is however very expensive be cause the sulfanilic acid (15 parts to parts of borneol) oxidizes away and therefore more chromic acid has to be used. i The present invention is based on the discovery thatif the solvent is added greduall to the mixture of chromic acid and borneol: the oxidation is effected quite uniformly and approximately theoretical yields are obtamed.

l By this process a It is quite immaterial whether concentrated or dilute chromic acid mixtures are employed. In all cases it is possible to eccel crate or moderate the progress of the oxidation by adding larger or smaller quantities.

having the right'melting-point can be produced with an almost theoretical yield.

The improved process may be carriedout as follows Example I: g. of sodium bichromate I are dissolved in 100 g. of Water, and g. of

sulfuric acid (S. Gr. '1, 8 1) are added to the solution. This concentrated chrome solution is then diluted with 1400 g., of water. When Specification of Letters Patent.

'AppLcetlon' filed November 18, 1912. Serial No. 73!,8782

perfectly pure camphor' Patented July 8,1913

this mixture has become cold, 100g. of"

neol or its equivalent isoborneol ere intro I duced therein, and then 5 of benzene" (C H or other non-oxidizzible solvent are added while stirring. This list addition is repeated every half-hour until in the course i is distilled ofl,

phor which without being further purified shows ameltingpoint of to 176 C.-

Exnmple II: 100 g. of sodium bichiO- mate are dissolved in 400 of within-and to this solution there are then added g.

of sulfuric acid, and-when cold, 100' of borneol. After having started iii-powerful stirring apparatus, the gradual adding ot. v i i is begun. The quantity of lien the solvent I zene (Z5 grams) which is to beaddedin order to dissolve completely the caniplion that is being formed is preferably sprczid.

over the period of' ztddition hours) as When all the benzene been addcd the stirr ng .18 continued for one houifi lofiiger; The benzeneramphor solution 13 then sepa-n washed in water end soda solution unti the color is completely discharged; Thenfi-FT ion ies

retedbut from the chromesolution end; 11??" dried withdcommon salt and filtered, Wll91 upon the solvent is distilled oft, leaving behind 95 parts of camphor which melts at 175 to 176 C. withoutv further purification.

The added amounts of benzene mentioned in the foregoing examples are naturally dependent on the degree of concentration of the chromic acid mixture'employed. The

process may be retarded at will by adding neutral solvent to a mixture of the borneol with ehromic acid gradually in quantities such that the heat of reaction produced by the oxidation will not cause an local overheating, substantially asdescri ed.

2. An improved processlfor the manufactureot camphor from borneol by oxidation with chromic acid, consisting in adding benzene to a mixture of the borneol with ehronuc acid gradually in quantities such that the heat 0} reaction produced by the i oxidation willnot cause any local overheat ing, substantially as described.

3. An improved process for the manufacture of camphor. from borneol by oxidation with chromic acid, consisting in gradually adding a neutral solvent to mixtures of concentrated chromic acid and 'borneol in small quantities at intervals.

4c. An improved process for the manufacture of camphor from borneol by oxidation with chromic acid, consisting in gradually adding to mixtures of concentrated chromic acid and borneol, small quantities of a new tral solvent.

5. An improved process for the manufacture of camphor from borneol by oxidation,

consisting in adding a neutral solvent to a'mixture of the borneol with chromic acid gradually in quantities such that the temperature of the oxidation mixture does not rise beyond 25 to 30 C., substantially as described. 4

In testimony whereof I affix my signature in presence of two witnesses.

" CARL RUDER.

l/Vitnesses:

ERNEST H. L. MUMMENIIOFF,

EDWARD Horr. 

